CD-4 - The thin line between success and failure, but still in the fight!

[Marcsten]

It's some kind of marketing thing, there are a couple others.
https://www.ebay.com/itm/1655695858...XiVzQXFlWLAn3bDPOk7N|ampid:PL_CLK|clp:2563228

Yeah I think something got lost in translation so to speak. Someone who was probably not even born when Quad was available, found this thing and heard that Quadradiscs play as stereo discs until they are run through the demod, which then converts them to quad, or something like that. CD-4 was great at some things but synthesizing quad from stereo wasn't one!

 

[J. PUPSTER]

When working with CD-4, I'm reminded of this old video, please, keep cool out there.

 

[Doug G.]

Must have been a Mac.

 

[fredblue]

When working with CD-4, I'm reminded of this old video, please, keep cool out there.

ah ha.. "Hulk-smashing" stuff up's more my big bruvva's style! (he's so good at it, i leave it to the expert of the family!

we're gluttons for punishment alright, Mister P!
(i'm so bonkers, this bank holiday weekend i've got my old Grundig Quadro demodulator out for a fiddle fart about.. 3 years after i packed it away when stuff started leaking out of the "Blend" switch round the back!

if you don't hear from me again, you know i've been blown up and CD-4's finally got the better of me!

 

[MidiMagic]

When working with CD-4, I'm reminded of this old video, please, keep cool out there.

He didn't do anything to the computer. He destroyed peripherals (keyboard and monitor).

 

[Gimme 4]

Does anyone have any or all of these Pioneer CD-4 test records? Wondering what the differences are. All made for Pioneer by JVC. I have the PQX-1014. (Wonder if there was a PQX-1013.) I also have two 12" Pioneer test records PLS-2001 and PL-2001S with CD-4 testing tracks which don't show up anywhere. They were issued to Pioneer's repair and QC departments, possibly sold to Pioneer authorized servicers too.

 

[Doug G.]

I'm sure the four different versions followed JVC's different versions. I don't know the exact differences but I know the first JVC version had either a track error having to do with adjusting separation on the two channels or the wording was incorrect.

JVC actually made the 45 RPM adjustment records for several different manufacturers.

Doug

 

[kfbkfb]

https://worldradiohistory.com/Archi...idelity/70s/High-Fidelity-1974-04.pdf#page=74^^^
...4DE-202...JVC remastered it (4DE-205)...


Info about the faulty JVC CD-4 setup disc (Involve Audio found that more than 12dB channel separation isn't needed, although I'd recommend trying to get ~15dB, just to have a safety margin).


edit: Lafayette 1974 catalog listing of the CD-4 demod (some specifications):
https://worldradiohistory.com/Archi...talogs/Lafayette-1974-Catalog-740.pdf#page=28

Kirk Bayne

 

[edisonbaggins]

ooh yes! if you turn the Front pair Off or right down low and listen out for Lead Vocals in each of the Rears (individually is best if possible) on The Spinners' S/T Track 1 or The Doobies' Toulouse Street Track 1 and then turn the Separation knobs down until you can barely hear those lead vocals, that should be helpful

Performed the patented FrederickBlue Spinners CD-4 Separation Callibration. Thanks for that.
My Spinners album happens to be pretty noisy/scratchy sounding. Is this the "sandpaper" effect I've heard about? Maybe I have a noisy copy? Surface looks ok, but not awesome.
Is there a known super-quiet, nice-sounding CD-4 album I can audition to check if I have the "sandpaper" issue? I don't recall this on The Best of The Doors.

 

[sjcorne]

Surface looks ok, but not awesome.

That's the funny thing about CD-4, the visual appearance of the LP seems to have no bearing on how it actually sounds.

 

[Quad Linda]

You can't tell whether the carrier has been damaged by viewing the vinyl.

Another angle is tracking force. Cartridges suggest tracking force. Try to stay within that range, but a smidge (1/8 - 1/4 add'l grams) above the lowest force. Otherwise, LP warpage could severely affect that, record wear, stylus wear and much more.

Have you used some sort of stylus pressure gauge and checked cartridge alignment with a disc or protractor?

Also recommend calibrating and/or resetting anti-skate device.

 

[edisonbaggins]

You can't tell whether the carrier has been damaged by viewing the vinyl.

Another angle is tracking force. Cartridges suggest tracking force. Try to stay within that range, but a smidge (1/8 - 1/4 add'l grams) above the lowest force. Otherwise, LP warpage could severely affect that, record wear, stylus wear and much more.

Have you used some sort of stylus pressure gauge and checked cartridge alignment with a disc or protractor?

Also recommend calibrating and/or resetting anti-skate device.

I have set the tracking force and anti-skate, just according to the TT manual. It's set to a smidge above 1 gram. I have a scale. I can bust it out, at some point.
I haven't done the protractor thing. Eyeballing, the angle looks like it should, according to the manual. But I'd like to learn more about that, in case I need to measure more accurately.

 

[Quad D]

I recommend tracking force near the maximum in cartridge specs. Also, experiment with carrier level knob, reducing the level as much as possible (while still having the CD-4 light illuminated) will reduce the sandpaper effects. When the light goes off, go a notch or more up to have it back on and listen. On good records this exact precision might not be necessary. Microline styluses (or true Shibata) will also reduce the sandpaper effect on bad records.
1 gram is super low for Shibata or Microline, so I guess you have an elliptical or HE, this will be more record dependent, harder for these types to get a damaged carrier signals from the groove. On good condition records no problem (usually).

 

[edisonbaggins]

I recommend tracking force near the maximum in cartridge specs. Also, experiment with carrier level knob, reducing the level as much as possible (while still having the CD-4 light illuminated) will reduce the sandpaper effects. When the light goes off, go a notch or more up to have it back on and listen. On good records this exact precision might not be necessary. Microline styluses (or true Shibata) will also reduce the sandpaper effect on bad records.
1 gram is super low for Shibata or Microline, so I guess you have an elliptical or HE, this will be more record dependent, harder for these types to get a damaged carrier signals from the groove. On good condition records no problem (usually).

Cartridge is an ADC ZLM. Not sure what the exact stylus is or how to verify that.
This Lafayette demod does not seem to have a carrier adjustment. For input, you can choose Hi or Lo though.

 

[kfbkfb]

Both the Vertical Tracking Angle and the "Overhang" should be set properly for CD-4 (and use the highest tracking force for the cart, too low cart tracking force means the stylus may lose contact with the record groove as the stylus is thrown around by the record groove, damaging the groove).

Amazon sells some inexpensive cart adjustment devices:
https://www.amazon.com/Turntable-Cartridge-Alignment-Vertical-Protractor/dp/B07S3Y7FXS

Kirk Bayne

 

[Quad D]

Cartridge is an ADC ZLM. Not sure what the exact stylus is or how to verify that.
This Lafayette demod does not seem to have a carrier adjustment. For input, you can choose Hi or Lo though.

It is an ADC version of elliptical.

 

[Quad D]

If you want to have headache free CD-4, I suggest AT VM540ML, or VM95SH if you like more neutral sound (no slight treble lift of 540).
If you like to keep XLM, you will have to work at it a bit more, or have good condition CD-4 records, and not cut super hot (strong signal).

 

[fredblue]

Performed the patented FrederickBlue Spinners CD-4 Separation Callibration. Thanks for that.
My Spinners album happens to be pretty noisy/scratchy sounding. Is this the "sandpaper" effect I've heard about? Maybe I have a noisy copy? Surface looks ok, but not awesome.
Is there a known super-quiet, nice-sounding CD-4 album I can audition to check if I have the "sandpaper" issue? I don't recall this on The Best of The Doors.

any of the Doobies discs are useful for setup, lead vocal near-wipeout in the Rears is what you're looking for on many (but not all) of the tracks.

AWB Side 1, Track 3, "Pick Up The Pieces", you should have the saxophone solo in the Rears only.

JT's "Gorilla" disc is another good one, you're looking for very very low level lead vocals in the Rears (total wipeout impossible i think?)

 

[fredblue]

Cartridge is an ADC ZLM. Not sure what the exact stylus is or how to verify that.
This Lafayette demod does not seem to have a carrier adjustment. For input, you can choose Hi or Lo though.

i think you need a different stylus or possibly ditch the cart altogether?

i think "Lo" would be for high output carts like ceramic/crystal etc. and "Hi" would be for Moving Magnet, like yours

 

[Quad D]

any of the Doobies discs are useful for setup, lead vocal near-wipeout in the Rears is what you're looking for on many (but not all) of the tracks.

AWB Side 1, Track 3, "Pick Up The Pieces", you should have the saxophone solo in the Rears only.

JT's "Gorilla" disc is another good one, you're looking for very very low level lead vocals in the Rears (total wipeout impossible i think?)

Have to be careful with this method, it can lead to too low fronts volume.